1. Field of the Invention
The present invention relates to a brush seal device for sealing a clearance formed between a shaft and its mating component that are relatively displaceable. More particularly, the present invention relates to a brush seal device for sealing a clearance formed between two components relatively displaceable, wherein a split brush-seal piece of a thin plate has a brush section on its one side and a base section on the other side and is formed with a projection on its one split face and a recess on its other split face, both the projection and recess being able to engage the corresponding recess and projection on the mating brush-seal pieces, respectively, and a plurality of split brush-seal pieces are connected in order to obtain a brush seal in any size.
2. Description of Related Art
As one related art to the present invention there exists a brush seal device 100, as shown in FIG. 14.
FIG. 14 is a sectional view of a brush seal device 100 mounted between a rotary shaft 120 and a casing 110 through which the rotary shaft 120 passes. The rotary shaft 120 and the casing 110 are components, such as of a steam turbine or gas turbine. The brush seal device 100 seals fluid by separating the space formed between the casing 110 and the rotary shaft 120 that displace relatively.
In FIG. 14, the brush seal device 100 is formed in a ring shape and secured in a channel section 112 of the casing 110. The brush seal device 100 has a brush seal 109 to which a backing plate 102 and support plate 103 are attached as its accessories. In the brush seal 109, bristles 101 are arranged in a circle to form a wall and coupled together at one end to form an attachment section 104. The free end 105 of the brush seal 109 faces the rotary shaft 120. The diameter of the bristle 101 used is generally 0.02 to 0.5 mm. Tens or hundreds of thousands of bristles are used for this purpose.
On one side of the brush seal 109 is located an annular backing plate 102 with its side face 108 in contact with the brush seal 109 and supports the bristles 101 against the action of the pressure of the sealed fluid.
Also, on the other side surface of the brush seal 109 is integrally placed a support plate 103 in the shape of a ring so as to, in cooperation with the backing plate 102, sandwich the brush seal 109 at its attachment section 104 side. The length of the support plate 103 in radial direction is made small so as to allow the brush seal 109 to be exposed to deform. One ends of the backing plate 102, attachment section 104 of the brush seal 109, and support plate 103 are welded together to form a coupling section 106.
FIGS. 15A and B are front views of part of the brush seal 109 shown in FIG. 14. The brush seal device 100 in FIG. 15A is in a state that the brush seal 109 and the rotary shaft 120 are normally fit each other such that there occurs no relative oscillation therebetween and the bristles 101 are straightly inclined in the rotational direction with respect to the radial direction of the rotary shaft 120. The normal state of the brush seal 109 is that the rotary shaft 120 contacts or approximates to the free end 105, as shown by the solid line in FIG. 14.
In the brush seal 109 formed in such a way described above, the larger the diameter of the brush seal 109 is, the more difficult the production thereof, due to the increase of the number of the bristles 101 to hundreds of thousands. Specifically, fixing the bristles 101 between the backing plate 102 and the support plate 103 while slanting the bristle 101, further increases its manufacturing cost.
Additionally, because the brush seal 109, backing plate 102, and support plate 103 are welded together into one piece, the backing plate 102 and the support plate 103 must have a larger thickness for strengthening them in a larger brush seal device 1. Thus, not only the yield of material is reduced by the increase of the number of the bristles, but also yield of material involved in the number of the backing plates 102 or the support plates 103 that can be cut out from one steel plate is reduced.
A brush seal device shown in FIG. 16 is another related art to the present invention. The brush seal device in FIG. 16, has a number of thin plates as a brush seal 209, that are piled in the circumferential direction of the rotary shaft 120 and seals a high pressure area P1 and a low pressure area P2.
Outer peripheral of the brush seal 209 is brazed to form an attachment section 104 and then mounted in a channel section of a casing 110 through the brazed attachment section 104. Also, a backing plate 102 is located on the side surface of the brush seal 209 that faces the low pressure area P2, a support plate 103 is located on the opposed side surface that faces the high pressure area P1, and thus both the plates 102 and 103 support the both side surfaces of the brush seal 209, respectively.
However, when the rotary shaft 120 eccentrically presses against the brush seal 209 that are formed in the way above, the brush seal 209 of piled thin plates forming an annular body is not given a space ample to deform itself, and the spring constant corresponding to the elastic deformation is therefore increased, which causes a problem such that it is difficult to follow the eccentric movement of the rotary shaft 60. To overcome this drawback, the clearance between the seal 209 and the outer circumference surface of the rotor 120 has been selected larger, but a problem concerning to the capability to prevent the leakage of fluid to be sealed is also present.
Additionally, the pressure of the sealed fluid acts on the seal 209 in the direction of the surfaces of the piled thin plates forming the seal 209 and, as the result, gaps are forcedly increased between the piled plates. Accordingly, also in this case, a problem concerning to the capability to prevent the leakage of fluid to be sealed is present.
Moreover, the brush seal 209 forming an annular body includes some hundreds of thousands thin plates used. Therefore, it is extremely difficult to fabricate the brush seal 209 and the yield of material is also poor. Further, as the length along the outer circumference of the annular body of the brush seal 209 is longer than that along the inner circumference, spacers are necessarily disposed on the outer circumference to compensate the difference in the circumferential length between the outer and inner circumferences. However, gaps still remain between the surfaces of the piled plates. In this viewpoint, there also exists the problem of sealing ability. Also, as a whole, the brush seal 209 constitutes a ring, thereby to cause its elasticity to be lost, so that the flexibility thereof may be reduced and the free end 105 of the brush seal 209 be worn quickly.
In the brush seal device 100 constituted as described above, when the rotary shaft 120 contacts the brush seal 109 involved in any vibration, oscillation or the like, the brush seal 109 is pressed to contact the rotary shaft 120, and at he same time its tilt angle is increased, as shown in FIG. 15B.
Referring to FIG. 14, the clearance C generated between the free end 105 of the bristles 101, at the position diametrically opposite to the position where the rotary shaft 120 presses against the brush seal 101 (in the state shown in FIG. 15B) becomes larger due to the oscillation of the rotary shaft 120, as shown by phantom line in FIG. 14, which will cause leakage of the sealed fluid though the clearance C. In order to prevent this leakage, the bristles 101 are slanted toward the rotational direction of the rotary shaft. However, because hundreds of thousands of bristles 101 are arranged to form a wall in a bundle as a seal device, the yield of material may become poor, and it may be extremely difficult to fabricate an attachment structure for slanting bristles 101.
Further, the bristles 101 of steel wire are forcedly separated to each other by the pressure of the sealed fluid, which also present a problem of its sealing ability.
Also, in the seal 209 in FIG. 16, because the thin plates are coupled along the direction of action of sealed fluid, the sealed fluid will pass or leak through gaps between the surfaces of neighboring plates. In addition, the flexibility of the free end 105 of the seal 209 must be reduced, clearance between the rotary shaft 120 and itself must be larger, and the problem of sealing ability also occurs. Also, the thin plates forming the seal 209 are layered one by one along the circumference of the rotary shaft 120, resulting in a large number of thin plates being required and yield of material being reduced. Further, the increase of material will adversely reduce the flexibility and the wear on the seal 209 is therefore accelerated by the friction generated at the tip of the seal 209.
The present invention has been made in consideration of the problems as described above, and therefore the technical problem is to enable the production of a brush seal having smaller parts of material regardless of its size, so that yield of material can be improved. Also, it is an object of the present invention to achieve to manufacture brush seals easier, so that production equipment cost can be reduced.
Also, it is another object of the present invention to easily form the attachment section and also easily mount the brush seal device to machinery and equipment without disassembling them. Also, it is still another object of the present invention to provide a brush seal easily replaceable when it is damaged.
In addition, it is yet another object of the present invention to increase the sealing ability of the brush seal.
The present invention has been made to solve the problems as described above, and technical means for solving the problems are constituted as described hereinafter.
The brush seal device of a preferred embodiment according to the present invention is one mounted on one of two components that are relatively rotated, for sealing the clearance given between the two components, comprising:
a brush seal having brush seal units made of thin plate, each brush seal unit having a brush section with slits on a side of the thin plate that faces the other component and having a base section on the opposing side that is fixed on the one component,
wherein the brush seal unit of the brush seal has a plurality of split brush-seal pieces, and each of the split brush-seal piece has on its split surfaces engagement portions, one having a projection and the other having a recess, which are capable of engaging a corresponding recess and a projection of mating split brush-seal pieces, respectively.
According to the brush seal device of a preferred embodiment of the present invention, the brush seal is divided into a number of split brush-seal pieces and each of the split brush-seal pieces has a projection and a recess in its both split surfaces, so that it is easy to position and assembly and the binding forces at the engagement section are strong.
Furthermore, the split brush-seal piece is small even if a brush seal device is larger, and therefore a number of split brush-seal pieces can be obtained from a thin plate, resulting in the improvement of the yield of material.
Further, because the attachment section of the brush seal is formed in the base section of a thin plate, the assembly work for stacking is facilitated in assembling the brush seal device. Moreover, the bristles on one side of a thin plate are formed in the shape of strips, so that the bristles integral with the attachment section is easily attached, and the plate-like bristles have effective ability to seal. Additionally, a number of split brush-seal pieces can be produced from a thin steel plate by etching process or the like, so that machining or processing is easy to perform, and equipment cost can be reduced.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2001-260129, filed on Aug. 29, 2001, the disclosure of which is expressly incorporated herein by reference in entirety.